The suicide rate among U.S. troops continues to climb, despite a sharp drop in combat activity. Some experts fear the problem will grow even worse this year.

New Pentagon numbers obtained by the Associated Press show military members committed suicide at a rate of almost one per day in 2012, 349 last year among active-duty troops. That's up from 301 the year before and exceeds the Pentagon's own internal projection of 325.

The Pentagon has made it a priority but is admittedly struggling with what Defense Secretary Leon Panetta and others call an epidemic.

"They're really trying to put their fingers on what exactly it could be," said retired Army Maj. and CBS military analyst Mike Lyons in an interview Tuesday with Seattle's Morning News. "There's really no silver answer, no silver bullet so to speak."

Last year's total is the highest since the Pentagon began closely tracking suicides in 2001. It exceeds the 295 Americans who died in Afghanistan last year, by the AP's count. According to Lyons, many troops are dealing with both the long term effects of a decade of combat in Afghanistan and Iraq coupled with the increasing fear and stress of getting forced out or isolated if they admit they're struggling.

"Army psychologists have identified a fear of being left behind. If a soldier now admits the fact having some kind of suicidal thoughts and he ended up not getting deployed or doesn't get promoted or doesn't get retained, that causes extra stress."

Although some military members might be worried about disclosing how they're really feeling, other advocates say the military hasn't done enough to help those that ask for help.

One such case was Army Spc. Christopher Nguyen, 29, who killed himself in August at an off-post residence he shared with another member of the 82nd Airborne Division at Fort Bragg, N.C., according to his sister, Shawna Nguyen.

"He was practically begging for help, and nothing was done," she said in an interview.

She said he had been diagnosed with an "adjustment disorder" — a problem of coping with the uncertainties of returning home after three deployments in war zones. She believes the Army failed her brother by not doing more to ensure that he received the help he needed before he became suicidal.

"It's the responsibility of the military to help these men and women," she said. "They sent them over there (to war); they should be helping them when they come back."

But Lyons said it's clear the Pentagon has made it a top issue and will continue seeking ways to help reduce the number of suicides as quickly as possible.

"The awareness level is very high on the military's radar and it's going to stay there," he said.

Lyons is hopeful the numbers will decline as the number of troops returning home from combat duty continues to drop over the next few years. But David Rudd, a military suicide researcher and dean of the College of Social and Behavioral Sciences at the University of Utah, said he's not optimistic.

"Actually, we may continue to see increases," he said, since the military is headed for major personnel cuts as budgets shrink. Fear of being compelled to return to civilian society is especially stressful for people whose identity and self-esteem is closely tied to their role in the military, Rudd said.

If there's any silver lining, the Pentagon says although the military suicide rate has been rising, it remains below that of the civilian population. It says the civilian suicide rate for males ages 17-60 was 25 per 100,000 in 2010, the latest year for which such statistics are available. That compares with the military's rate in 2012 of 17.5 per 100,000.